Recently, there has been developed, as a form of an electric vehicle, a vehicle of a so-called in-wheel motor type which has electric motors inside or near the corresponding wheels (unsprung portions) of the vehicle and which drives the wheels directly by means of the electric motors. In such a vehicle of an in-wheel motor type, rotations of the electric motors provided for the corresponding wheels are controlled individually. Namely, by means of individually performing drive (power running) control or regenerative control for the motors, driving forces or braking forces to be applied to the respective wheels can be controlled individually in accordance with the traveling state of the vehicle.
Regarding such a vehicle of an in-wheel motor type, for example, Patent Document 1 listed below discloses a braking-driving force control device of a vehicle which applies different braking/driving forces to the respective wheels so as to suppress vibration of the vehicle in the vertical direction accompanying a pitching behavior of the vehicle which occurs when the vehicle is running over a stepped portion, etc. of a road surface, to thereby reduce a pitching moment generated around the vehicle's center of gravity.
Patent Document 2 listed below discloses an in-wheel motor system in which the diameter of a smallest-diameter portion of a wheel rim is rendered sufficiently large in relation to the outer diameter of a tire so as to enable a high-power motor to be installed in the wheel rim, and the vertical spring constant of the tire can be made far smaller than that of a tire which has the same size and an ordinary cross sectional shape so as to assure satisfactory riding quality in terms of vibration and sufficient resistance to shock caused by a large input.